This study will examine the effects of seizures on regional brain metabolism, and the neuronal anatomic organization of language skills, in children at high risk for developing refractory epilepsy. This population provides an opportunity to gain insight into the general development of human language abilities. Subjects with early onset of epilepsy should exhibit greater plasticity of neuronal reorganization than those with later onset. We will also study the appearance, extent, and magnitude of regional glucose metabolic abnormalities associated with the epileptogenic zone. Children will be evaluated with interictal FDG-PET, volumetric 1.5 Tesla MRI, and 1.5 Tesla MRI-based functional mapping. All data will be coregistered with 1.5 Tesla MRI to facilitate intrasubject regional comparison over three years, as well as to account for inter-subject variability of language activation patterns. Subjects will be identified within one year after onset of epilepsy and followed longitudinally for three years. As a result of this study new strategies will be developed to assist in the early assessment of intractability, and hence identify those children most likely to benefit from early surgical intervention. Non-invasive means of identifying cortical language representation will help in selecting children for surgical treatment as well as assist in determining surgical approaches to minimize excision of language cortex. A greater understanding of the anatomic organization of language during critical periods of cognitive development and neuronal plasticity will be gained. While pursuing these aims the investigator will develop a sound background in multimodality: imaging research methods and techniques, including computer based statistical analysis of imaging data, and expertise in the utilization of fMRI as a tool for anatomic location of cerebral function.